1. Field of the Invention
This invention pertains to centrifugal separators for fluid. More particularly, it pertains to pitot pumps for separating contaminants, such as viscous liquids or solids, from princiipal fluids and for pumping the cleaned principal fluid.
2. Review of the Prior Art
Pitot pumps are a form of centrifugal pump and typically include a hollow rotatable casing disposed within a surrounding housing, means for delivering a fluid to be pumped to the casing, and a pitot tube fixed in the casing for collecting fluid at a desired point in the casing spaced from its rotational axis with a ram effect. Such pumps also include a discharge system for receiving fluids from the pitot tube and for discharging the same at a desired pressure coaxially of the casing. Such pitot pumps are shown in U.S. Pat. Nos. 3,795,459, 3,817,659 and 3,838,939, all of which are owned by the assignee of this invention.
Pitot pumps are used for many purposes. One use, which illustrates the problems to which this invention is addressed, is to supply motive pressurized liquid to a hydraulic pump located in the bore of an oil well for pumping oil out of the well into a suitable collection facility. In such an application, the motive fluid for the well bore pump may be a portion of the oil produced from the well itself and supplied to the inlet of the pitot pump. Very often, however, the oil taken from the well contains contaminants, notably sand, which should be removed from the oil before it is returned under pressure to the pump located in the well; the presence of sand in the pressurized oil supplied to the well bore pump produces undue wear and damage to this pump. It has, therefore, been proposed to construct a pitot pump, to which oil is supplied from the well for pressurization prior to return to the well bore pump, as both a pump and as a centrifugal separator in which sand or other contaminants are removed from the oil as the oil is pressurized, i.e., pumped. See, for example, U.S. Pat. No. 3,817,446 owned by the assignee of this invention.
Experience with the pitot pump-separators of the character shown in U.S. Pat. No. 3,817,446 has shown that sand and other solid or heavy viscous contaminants in the principal fluid tend to accumulate on the inner walls of the rotatable casing adjacent its outer periphery and thereby clog or plug the ducts and jets provided generally radially through the casing outer periphery. These ducts and jets discharge the contaminants from the casing into the housing separately from discharge of the principal fluid from the pump-separator coaxially of the casing. Such clogging of the contaminant discharge ducts and jets is a major one of the several problems to which this invention is successfully addressed; other ones of these problems, and the solutions of the same, are made apparent hereinafter.